Common treatment for inflammatory bowel disease is linked to reduced Covid-19 antibody response

Published: 30 March 2021

New evidence indicates that the commonly-prescribed inflammatory bowel disease (IBD) drug infliximab blunts the immune system to Covid-19 infection, potentially increasing the risk of reinfection, according to research co-authored by St George’s Professor Richard Pollok and Dr Kamal Patel.

The findings arose from the CLARITY study, which recruited 6,935 patients with Crohn’s disease and ulcerative colitis from 92 UK hospitals between September and December 2020.  It found that fewer than half of people with IBD who were treated with infliximab had detectable antibodies after Covid-19 infection.

The study is led by gastroenterologists at the Royal Devon and Exeter NHS Foundation Trust and the University of Exeter Medical School and supported by Crohn’s and Colitis UK and the UK National Institute for Health Research (NIHR). St George’s was among the top recruiting sites for the study, with 150 participants.

The authors say an impaired immune response may boost susceptibility to recurrent Covid-19 and help drive the evolution of new variants of the virus, warn the researchers. However, they are encouraging people to continue to take their medication as overall Covid-19 risk remains very low.

Careful monitoring of patients with IBD treated with infliximab, who have been vaccinated against Covid-19, will be needed to ensure they mount a strong enough antibody response to ward off the infection, they advise.

CLARITY study lead, Professor Tariq Ahmad, of the University of Exeter Medical School, said, “The poor antibody responses observed in patients treated with infliximab raise the possibility that some patients may not develop protective immunity after Covid-19 infection, and might be at increased risk of reinfection.  What we don’t yet know is how use of anti-TNF drugs will impact antibody responses to vaccination.”

Professor Richard Pollok, co-author on the paper from St George’s, University of London and St George’s Hospital, said, “This study emphasises the need for research to better understand the impact of the pandemic on people with bowel conditions. Further work will now continue to find out if different vaccine schedules might be required for patients with IBD who are on immunosuppressive drugs.

He added, “this work could not have happened without the very helpful patients who attend the infusion suite at St George’s.”

500,000 people across the UK live with IBD, of which ulcerative colitis and Crohn’s disease are the two main forms. Symptoms include urgent and frequent bloody diarrhoea, weight loss, pain, and extreme fatigue. At the start of the Covid-19 pandemic the UK Government advised that patients taking anti-TNF medicines could be at increased risk of complications from coronavirus. All were advised to follow strict social distancing measures, and some, depending on the severity of their condition, were advised to shield.

Sarah Sleet, Chief Executive Officer at Crohn’s & Colitis UK, said, “The CLARITY results are an important first step in helping us understand how different medicines for Crohn’s and Colitis affect a person’s response to coronavirus.  At this stage the key message is people with Crohn’s and Colitis should keep taking their medication to stay well and take the vaccine when offered. But we also need research like this to continue. A huge number of people with Crohn’s and Colitis have had to contend with the stresses of shielding and social distancing, and it’s vital this group is prioritised in research.”